{Cu²⁺–Co³⁺–Cu²⁺} and {Cu²⁺–Fe³⁺–Cu²⁺} Heterobimetallic Complexes and Their Catalytic Properties

Abstract

We report on the heterobimetallic complexes {Cu + -Co 3+ -Cu + } (3), {Cu + -Fe 3+ -Cu + } (4), {Cu 2+ -Co 3+ -Cu 2+ } (5), and {Cu 2+ -Fe 3+ -Cu 2+ } (6) and show their catalytic applications in the oxidation of hindered phenols and the oxidative coupling of terminal alkynes. The former reaction produces C-C-coupled and dealkylated products, whereas the latter leads to [a] 2113 the homo-and heterocoupling of terminal alkynes. The facile redox interconversion between Cu + and Cu 2+ for the secondary metal ions in these heterobimetallic complexes appears to be essential for the observed catalysis, and an important design aspect is better substrate accessibility and the use of molecular oxygen as the sole oxidant.portant classes of compounds. [6] Interestingly, both these reactions are oxidative in nature and the presence of a redoxactive metal facilitates the transformation. [7] Therefore it is important to design catalysts that provide redox-active metals with better substrate accessibility and transformation ability. In this context, metalloligands 1 and 2 have been shown to accommodate a variety of secondary metal ions while maintaining substrate accessibility. [3] Importantly, Lewis acidic secondary metal ions in the resultant heterobimetallic complexes and networks facilitate Beckmann rearrangement, ring-opening, and cyanation reactions, [3] whereas the presence of Cu I ions with accessible Cu 2+/+ red-Scheme 1. Metalloligands and heterobimetallic complexes discussed in this work. Crystal StructureHeterobimetallic complexes 5 and 6 are isostructural, however, one of the representative complexes, compound 5, was crystallographically characterized. [11] Complex 5 crystallizes in a triclinic cell system with the P1 space group. A thermal ellipsoidal representation of complex 5 is shown in

Design and synthesis of coordination polymers with chelated units and their application in nanomaterials science

“…A great number of metalloligands is developed, which provide targeted production of ordered heterometallic architectures. [93][94][95][96][97][98][99] Interesting heterometallic Cu(II)-Zn(II) CPs 2A and 2B are synthesized by interaction of CuL metalloligand, where H 2 L ¼ N,N 0 -bis(salicylidene)-1,3propanediamine, with Zn perchlorate and sodium dicyanamide (dca) using different molar ratios of reagents (Scheme 2). 100 The obtained compounds are 2D and 3D CPs, respectively, with a common [(CuL) 2 Zn(N(CN) 2 ) 2 ] trinuclear unit, in which dca fragments have m 1,5 -bridging coordination regime.…”

Visible‐Light‐Driven di‐t‐Butyl Peroxide‐Promoted the Oxidative Homo‐ and Cross‐Coupling of Phenols

“…2,2′,6,6′‐tetramethyl‐4,4′‐biphenol ( 2 f ): [22] mp 221–223 °C. According to the general procedure, purification via silica gel column chromatography (ethyl acetate/petroleum ether, 1/20) afforded a colorless solid.…”

“…1 H NMR (400 MHz, CDCl 3 ) δ 1.40 (s, 18H), 1.83 (s, 6H), 2.26 (s, 6H), 4.81 (s, 2H), 7.14 (s, 2H). 13 C NMR (100 MHz, CDCl 3 ): 15.9, 20.0, 29.6, 34.5, 121.0, 128.1, 128.8, 133.4, 134.1, 150.4 2,2',6,6'-tetramethyl-4,4'-biphenol (2 f): [22] mp 221-223 °C. According to the general procedure, purification via silica gel column chromatography (ethyl acetate/petroleum ether, 1/20) afforded a colorless solid.…”

Three-Dimensional Heterometallic Coordination Networks: Syntheses, Crystal Structures, Topologies, and Heterogeneous Catalysis

“…[41][42][43][44][45][46][47][48][49][50][51][52][53][54] Depending on the number, position, and orientation of the appended functional groups being offered from a metalloligand; we have been able to showcase the synthesis of hydrogen bonded assemblies, 41,42 trimetallic complexes [43][44][45][46] as well as ordered 2D and 3D architectures. [47][48][49][50][51][52][53][54] These examples illustrate the importance metalloligands for the construction of HCNs compared to homometallic networks typically obtained from the conventional reaction between a ligand and a metal ion.…”

“…In addition, judicious selection of the Lewis acidic and/or redox-sensitive secondary metals in such designed materials has been utilized by displaying homogeneous as well as heterogeneous catalysis. [43][44][45][46][47][48][49][50][51][52][53][54] Herein, we report the syntheses, crystal structures, topological analyses, and catalytic properties of two {Co 3+ -Zn 2+ } and two {Co 3+ -Cd 2+ } HCNs using two different Co 3+ -based metalloligands offering appended aryl carboxylic acid groups. These HCNs display interesting network topologies including one unprecedented topology.…”